dnsproxy: Check cache for TCP request before connecting to server

It is not necessary to create TCP sockets to server if we have
the answer already in the cache.

diff --git a/src/dnsproxy.c b/src/dnsproxy.c
index dc8ab13..82c5c1f 100644 (file)
--- a/src/dnsproxy.c
+++ b/src/dnsproxy.c
@@ -2450,7 +2450,8 @@ static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
        socklen_t client_addr_len = sizeof(client_addr);
        GSList *list;
        struct listener_data *ifdata = user_data;
-       int waiting_for_connect = FALSE;
+       int waiting_for_connect = FALSE, qtype = 0;
+       struct cache_entry *entry;
 
        DBG("condition 0x%x", condition);
 
@@ -2507,6 +2508,35 @@ static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
        req->ifdata = (struct listener_data *) ifdata;
        req->append_domain = FALSE;
 
+       /*
+        * Check if the answer is found in the cache before
+        * creating sockets to the server.
+        */
+       entry = cache_check(buf, &qtype, IPPROTO_TCP);
+       if (entry != NULL) {
+               int ttl_left = 0;
+               struct cache_data *data;
+
+               DBG("cache hit %s type %s", query, qtype == 1 ? "A" : "AAAA");
+               if (qtype == 1)
+                       data = entry->ipv4;
+               else
+                       data = entry->ipv6;
+
+               if (data != NULL) {
+                       ttl_left = data->valid_until - time(NULL);
+                       entry->hits++;
+
+                       send_cached_response(client_sk, data->data,
+                                       data->data_len, NULL, 0, IPPROTO_TCP,
+                                       req->srcid, data->answers, ttl_left);
+
+                       g_free(req);
+                       return TRUE;
+               } else
+                       DBG("data missing, ignoring cache for this query");
+       }
+
        for (list = server_list; list; list = list->next) {
                struct server_data *data = list->data;